Is bigger always better? Modern concepts in the design of dental restorations.

This poster will investigate dental restorations defined as “any type of dental filling or crown, which is aimed at restoring a tooth to its normal form, function and appearance” (1). There is evidence that the Chinese used silver paste as a type of amalgam restoration as early as 700 A.C. (2). Today, the surgical removal of carious lesions from teeth continues to be a large part of a dentist’s job (3). Many dentists and dental schools still refer to the guidance given by GV Black’s classification of cavity design, although this was first published in 1908 (4). Over recent years, Black’s guidance for the preparation of teeth for restoration has been criticized because the architectural design of the cavity and resulting restoration needed for it, is deemed excessively large and involves unnecessary and unacceptable loss of natural tooth (5). Miles Markley, a leading figure in minimally invasive dentistry, has argued the case for minimal intervention for over 50 years (6). Markley believes any loss of natural tooth should be considered a serious injury and that the preservation of healthy, natural tooth structure should be the focus of all dental professionals (6). This poster aims to investigate whether advances in medical science and technology could help dentists to preserve teeth for longer by adopting a minimally invasive approach to dental restorations. It will explore whether Black’s approach to dental restoration is still preferable to practice, or if the smaller less damaging innovative restorations are preferable to patients and to the functioning, aesthetics and lifespan of teeth.

After careful review of the literature, it is clear that a minimally invasive approach to tooth restoration is the preferred choice for the long-term future and functionality of teeth; a minimal restoration, which utilises the best technological advances, tools and research is far superior to the destructive and larger restorations advocated by GV Black (4). A minimally invasive approach to dentistry does however have its limitations. According to Professor Paul Brunton, only 50% of the population visit their dentist regularly (13). Minimally invasive dental restorations may therefore not be possible in populations where early diagnosis and intervention is prohibited as a result of non-compliance, lack of resource or lack of access to dental care.

Introduction

Discussion and Conclusions

Results

SCHOOL OF DENTISTRY Liverpool, L69 3GN, UK. email: a.l.galloway@student.liverpool.ac.uk

1.  The Oxford Concise Medical Dictionary. Ninth Edition. Oxford: Oxford University Press, 2015:655. 2.  American Dental Association. History of Dentistry Timeline. 2017.

http://www.ada.org/en/about-the-ada/ada-history-and-presidents-of-the-ada/ada-history-of-dentistry-timeline (acccessed 11/02/17).

3.  Tyas MJ, Anusavice KJ, Frencken JE, Mount. GJ. Minimal Intervention Dentistry: A Review. FDC Commission Project 1-97. International Dental Journal. 2000;50(1):1-12.

4.  Black GV. A Work on Operative Dentistry: The Technical Procedures in Filling Teeth. Chicago: Medico-Dental Publishing Company, 1908.

5.  Mount GJ. Minimal Intervention Dentistry: Cavity Classification and Preparation. 2009. http://www.moderndentistrymedia.com/may_june2010/mount.pdf (accessed 17/01/17).

6.  Markley M. (1951) cited in: Murdoch-Kinch CA & McLean ME. Minimally Invasive Dentistry. Journal Of American Dental Association. 2003;134: 87-95.

7.  Murdoch-Kinch CA & McLean ME. Minimally Invasive Dentistry. Journal Of American Dental Association. 2003;134: 87-95.

8.  Spie Digital Library. Red-shifted fluorescence Of Sound Dental Hard Tissue. 2011. http://biomedicaloptics.spiedigitallibrary.org/article.aspx?articleid=1166937 (accessed 12/02/17).

9.  Channel 4 News No more dental drilling and filling. 2011. https://www.channel4.com/news/no-more-dental-drilling-and-filling (accessed 17/01/17).

10. Mount GJ & Hume WR. A Revised Classification of Carious Lesions by Site and Size. Quintessence Int. 1997;28:301-303.

11. Biomimetic Dentistry CE. Biomimetic Dentistry: The techniques and scientific foundation to take your dentistry to the next level. 2012. http://www.biomimeticdentistryce.com/what-is-biomimetic-dentistry/ (accessed 08/01/17).

12. Ames A. Biomimetic Dentistry – An Explanation By Dr. Margaret Ames. 2015. https://m.youtube.com/watch?v=7pEYsdxaG1k (Accessed 18/01/17).

13. Brunton P. cited in: Channel 4 News (2011) No more dental drilling and filling. 2011. https://www.channel4.com/news/no-more-dental-drilling-and-filling (accessed 17/01/17).

Methods

One of the main criticisms of GV Black’s guidance on the restoration of teeth, is the reactive and overly aggressive/destructive approach to the treatment of caries and cavity preparation required to facilitate this (4). A key concept of academics supporting a minimally invasive approach to dental caries is the recognition that caries is a bacterial and infectious disease, which is preventable and at worst treatable with sometimes no or minimal surgical intervention (5). However, a minimally invasive approach can only be realised if bacterial disease can be detected, diagnosed, intercepted and treated microscopically at a very early stage; research to improve methods of early caries detection is on-going (7). Early detection is also dependant on patients being seen regularly by dentists and educated well on the care and maintenance of their teeth. Advances in diagnostic techniques including use of binocular loupes and headlights, radiography, quantitative laser fluorescence (figure 2) and tuned aperture computed tomography (7), can also facilitate in the early management and treatment of caries. Figure 2: Laser Fluorescence. (8) Understanding the disease process is particularly important, as infectious disease (caries) should not always be treated by surgery alone (5). Early carious lesions can be treated without surgery by altering the oral environment to facilitate tooth remineralisation, providing diagnosis is made before a cavitated lesion presents (7). Topical fluorides can increase

the availability of fluoride ions around carious lesions to facilitate tooth remineralisation as well as the formation of fluoroapatite, which increases the tooth’s resistance to demineralisation (3). Credentis AG is currently trialing a compound worldwide, which can temporarily fill microscopic holes in the teeth caused by bacterial acids in the mouth (9). The action of the compound along with the body’s natural defence system allows the tooth’s enamel to regrow (9). This type of restoration requires early diagnosis, is non-invasive and seems to restore integrity and strength of a natural tooth. Whilst surface cavitation may be treatable without the need for surgical intervention, surgical preparation of a cavity for more advanced lesions is required to eliminate and control disease progression (5). A growing body of opinion seems to favour a minimally invasive approach for surgical restoration of teeth, as once natural tooth is removed in preparation for a restoration, the remaining tooth structure will be weaker and subject to further breakdown in the future (5). Mount and Hume have proposed a replacement classification for the preparation of carious lesions (figure 3) to replace that of GV Blacks classification in order to minimalize restoration size and preserve as much natural tooth structure as possible (10): Figure 3: Mount-Hume Classification System. (10)

Minimal cavity design can be improved with the use of new and technologically improved tools available for cavity preparation. Air abrasion, tunnel preparation and laser cavity preparation are particularly advantageous for cavity preparation, as carious tooth structure can be removed while selectively maintaining healthy dentin and enamel (7). Once a cavity has been prepared, choice of restorative material can be considered, but fundamentally choice should be based on the material’s ability to withstand load, adhere and seal the margins well to protect against micro-leakage; this ensures any remaining bacterial infection within the cavity is isolated preventing further disease progression (5). Glass Ionomer Cements (GIC’s) are especially beneficial as a restoration material as they adhere well and release fluoride, calcium and aluminium ions into the tooth and saliva; this promotes remineralisation of demineralised tooth structure and increases resistance to future demineralisation due to the formation of fluoroapatite (7). Minimally invasive dentistry also supports the repair rather than replacement of restorations. This is because eventual loss of a tooth following repeated and larger restorations creates an inevitable cycle, which will ultimately lead to the loss of a tooth as any residual natural tooth structure is progressively drilled away (5). Biomimetic dentistry is an innovative technique used for dental restorations. Biomimetic translates as ‘mimics life’, and is minimally invasive and non-amputational, only removing what is necessary to preserve as much natural tooth structure as possible (11). Fluorescence and a laser are used to ensure only infected and broken down tooth structure is removed; tooth structure which is demineralised, is re-mineralised whenever possible instead of being removed (12). A biomimetic restoration has 5 layers so that the restoration once complete is stronger, more flexible and because the micro-gap of the closely bonded material is less than 1 micron, not even a single bacteria can get underneath the restoration (12). Whilst this type of restoration is time-consuming, the overall result is a restorative tooth structure, which mimics natural dentin as closely as possible (12). The bond strength of a biomimetically restored tooth is 400 times greater than a traditional restoration, and this is the same strength at which natural enamel bonds to dentin (11).

Whilst a minimally invasive approach is clearly preferable, there are huge cost implications associated with these types of treatment. The tools required are expensive and the time required to complete treatments is far greater than for traditional treatments. The way dentistry is currently funded for the majority of people mean reimbursement programmes need to change to accommodate the time and resources needed for minimal intervention dentistry, and encourage dentists to treat their patients in the best and most appropriate way (7).

References

Sourcing information for the poster began at Liverpool University library. Books, journals and e-sources were accessed using Medline, Google Scholar and YouTube, to facilitate the study of as much relevant literature as possible. Following on from this, a Sp ider D iagram of ideas was formulated (figure1). The Spider diagram helped to identify the main areas for investigation and study. Subsequent to this, a plan for the poster was devised. I used Microsoft Word to write the text, and this was then copied and pasted into the Microsoft PowerPoint Template from Vital.

Annabelle Galloway

Figure 1: Spider diagram.